Messages in this thread |  | | From | Andreas Dilger <> | Date | Thu, 5 Sep 2002 15:25:16 -0600 | Subject | Re: Uptime timer-wrap |
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On Sep 05, 2002 16:16 -0400, Richard B. Johnson wrote: > I tried to simulate your observation by making a driver that > set the 'jiffies' count upon an 'open'. The idea was to get > the jiffies count to something close to wrap so I didn't have to > wait a long time. > > Anyway, I found that setting the jiffies count to more than a > few hundred counts into the future, causes the machine to halt > with no interrupts (no Capslock, no NumLock, no network ping, etc). > > The machine just stops and I don't understand why. > > > spin_lock_irqsave(&xlock, flags); > jiffies += 0x1000; > spin_lock_irqrestore(&xlock, flags); > > ... works just fine, but, changing 0x1000 to 0x7fffffff causes > the machine to stop as reported. > > Does anybody have a clue?
Yes, because now some kernel code is going to wait 147 days - 1s or something like that to finish.
See Tim Schmielau <tim@physik3.uni-rostock.de> patch for testing jiffies wrap. It _initializes_ jiffies to a high pre-wrap value, maybe 5 minutes before wrap, instead of playing around with the jiffies value after the system is running.
Cheers, Andreas -- Andreas Dilger http://www-mddsp.enel.ucalgary.ca/People/adilger/ http://sourceforge.net/projects/ext2resize/
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